Insight into the role of Ti 3+ in photocatalytic performance of shuriken-shaped BiVO 4 /TiO 2−x heterojunction

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Applied Catalysis B: Environmental, ISSN: 0926-3373, Vol: 203, Page: 526-532

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Yunqing Zhu; Muhammad Wajid Shah; Chuanyi Wang
Elsevier BV
Chemical Engineering; Environmental Science
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Heterojunction is recognized as an effective approach to improve photocatalytic performance, but a well-matched energy band alignment is critical therein. In this work, the shuriken-shaped BiVO 4 /TiO 2−x heterojunction is built by engineering the electronic structure of TiO 2 with Ti 3+ self-doping via a two-step hydrothermal process to achieve a high photocatalytic performance. The presence of Ti 3+ creates a defect energy level under the conduction band of TiO 2, and thereby diminishes the interfacial energy barrier between BiVO 4 and TiO 2. The Ti 3+ defect energy level promotes the electron transfer from BiVO 4 to conduction band of TiO 2−x. The test of phenol degradation under 300 W Xenon lamp equipped with UV cut-off filter (λ ≥ 420 nm) demonstrates that BiVO 4 /TiO 2−x heterojunction exhibits higher photocatalytic activity than its counter parts, pure BiVO 4 and the physic mixture of BiVO 4 and TiO 2−x. The improved photocatalytic performance is mainly attributed to the heterojunction formed between BiVO 4 and TiO 2−x, which improves the separation of photogenerated charge carriers as support by comparative photocurrent and time-resolved PL spectral measurements. In addition, Ti 3+ self-doping also narrows the bandgap of TiO 2 and enhances the visible-light activity of TiO 2. The holes of TiO 2−x transfer to the valance band of BiVO 4 which further significantly improves the separation of photogenerated charge carriers, further. Additionally, the high surface area caused by TiO 2-x also contributes to the improved photocatalytic efficiency.